Staff: Mentor

The best laboratory vacuum has a pressure of about 1.00 x 10-18 atm, or 1.01 x 10-13 Pa. How
many gas molecules are there per cubic centimeter in such a vacuum at 293K?

PV = nkT
P/kT = n/V = N (# of molecules per cm^3)

Since V is typically in units of m^3 or liters, should I make my volume .01V to account for the cm^3?

When making unit conversions, use the trick of multiplying by "1" to help you do the unit conversion.

So to convert from cm^3 to m^3 multiply by "1" like this:

[tex]1cm^3 * \frac{(1m)^3}{(100cm)^3}[/tex]

The cm^3 unit terms in the numerator and denominator cancel (just like numbers cancel if they are identical in the numerator and denominator of a fraction), and you are left with what in units of m^3? Hint -- It's not 0.01 ...